水稻冠层光截获与叶面积和产量的关系

Relationship of PAR Interception of Canopy to Leaf Area and Yield in Rice

【目的】旨在解析水稻(Oryza sativa L.)冠层光合有效辐射(PAR)截获量及其分布与叶面积和产量的关系。【方法】以2个不同株型水稻品种为材料,设置高、中、低3个施氮水平,构建不同的群体冠层结构,于拔节至成熟期系统测定水稻冠层PAR截获量及其分布、以及叶面积和产量。【结果】水稻群体向上累积叶面积指数的垂直分布呈S型曲线,符合Logistic方程(R2>0.99);抽穗期、抽穗后17d和成熟期的冠层最大叶面积密度分别出现在0.53、0.56和0.60的相对冠层高度左右;随生育进程的推进,冠层上中部的相对叶面积密度呈递增趋势,而冠层下部的相对叶面积密度呈递减趋势。PAR截获率(FIPAR)与向下累积叶面积指数之间的关系可用方程FIPAR=α×(1-e-K×LAI)来定量描述(R2>0.86);消光系数K随生育进程的推进而递减,其日变化表现为早晚较高、中午较低。冠层PAR截获量(AIPAR)随生育进程的推进呈多峰分布,最高峰出现在移栽后58-70d,即孕穗至抽穗期,且随施氮量的增加而增大;在典型晴天下,冠层PAR截获量的日变化呈单峰分布,最大值出现在11:00-13:00。【结论】水稻群体叶面积的垂直分布影响冠层光截获;水稻产量与PAR利用率呈正相关,而PAR转化率随PAR截获量的增加呈先增大后减小的趋势,因此维持一定的漏光损失量对水稻高产有利。

【Objective】 The amount of photosynthetically active radiation （PAR） interception and distribution within canopy affects crop photosynthesis and biomass production. The primary objective of this study was to elucidate the relationship of PAR interception of canopy to leaf area and yield of rice （Oryza sativa L.） under different nitrogen rates for different cultivar types. 【Method】 Two field experiments were conducted at Nanjing in 2007 and 2008 rice growing seasons,involving two rice cultivars and three nitrogen rates. The amount of PAR interception and its distribution at different canopy heights,leaf area and yield of two cultivars were measured from jointing to maturity. 【Result】 The results indicated that the vertical distribution of upward cumulative leaf area index （LAI） followed a sigmoid curve,which could be described well with Logistic equation （R20.99）. The maximum leaf area density in heading,17 days after heading and maturity stages appeared at 0.53,0.56 and 0.60 of relative canopy height,respectively. The relative leaf area density of upper and middle canopy increased with rice development progress,but the relative leaf area density of basal canopy decreased with rice development progress. The relationship between fraction of PAR interception （FIPAR） and downward cumulative LAI could be described with a negative exponential equation as FIPAR=α×（1-e-K×LAI） （R20.86）. Diurnal variation of extinction coefficient （K） at noon was smaller than in the morning and afternoon,and the value of K decreased with rice development progress. The amount of PAR interception （AIPAR） showed multi-peaks distribution during rice development period,and the maximum peak appeared at 58-70 d after transplanting,around booting to heading stages. The AIPAR increased with increasing nitrogen application rate. Diurnal variation of AIPAR showed one peak distribution on the clear days,and the maximum AIPAR appeared at 11：00-13：00 in rice canopy. 【Conclusion】 The vertical distribution of leaf area affects PAR interception within rice canopy. The grain yield of rice was positively related to the PAR use efficiency,while PAR conversion efficiency first increased and then decreased with increasing PAR interception,thus it is benefit to have some penetration loss of PAR in rice canopy for high grain yield.